Mervyn King, Mark Carney‘s predecessor as governor of the Bank of England, in his final years in charge liked to compare the U.K. economy to a ship on storm-tossed seas. Calmer waters were always just ahead; the BOE’s gentle hand was on the tiller.

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Mark Carney, governor of the Bank of England

Mr. Carney, in his debut news conference on Wednesday as head of Britain’s storied central bank, ditched the evocative metaphors and instead delivered his revolutionary message in the dry language beloved of his central bank peers, as he unveiled the rate-setting Monetary Policy Committee‘s new strategy to steer the U.K. economy back to health: forward guidance.

Mr. Carney explained that he and his colleagues on the MPC have vowed to keep the BOE’s benchmark interest rate at a record low of 0.5% at least until the U.K.’s unemployment rate drops to 7%, barring any uptick in the likely path of the rate of inflation and assuming that ultralow rates don’t start to threaten the stability of the financial system.

The MPC can also abandon its commitment to low rates if public expectations of the future rate of inflation start to drift away from the BOE’s 2% annual inflation target.

Mr. King long resisted such commitments. Observers said Mr. Carney, who at the BOE heads an often factious committee of nine, came across as a confident leader as he set out the MPC’s plans.

“He really hit the ground running,” said Andrew Goodwin, senior economic adviser to the Ernst & Young Item Club, an economic forecasting group. “There was a real sense of a new broom.”

As the first foreigner appointed to the head the BOE in its 319-year history, the 48-year-old Mr. Carney arrived in the U.K. with a considerable burden of expectations on his shoulders. He has already been described by Treasury chief George Osborne as the outstanding central banker of his generation.

Where Mr. King preferred to keep reporters’ focus on the big picture, Mr. Carney was unafraid to delve into the minutiae of economic developments as he answered questions for more than 45 minutes. His remarks touched on home loan-to-income ratios when quizzed about the housing market, and he rattled off details about euro-zone policy initiatives when discussing the prospects for the U.K.’s neighboring economy.

Analysts noted that Mr. Carney appeared more willing to canvass the views of his MPC colleagues at Wednesday’s debut than Mr. King. During his long tenure, the newly ennobled Mr. King usually dominated the BOE’s quarterly news conferences, despite the presence of other senior officials.

Mr. Carney, by contrast, frequently brought in Charles Bean, deputy governor for monetary policy; Spencer Dale, the BOE’s chief economist; and Paul Fisher, the central bank’s markets chief during the question-and-answer session. He demonstrated an interest in fostering “a team culture in a way that Lord King never did,” said Nick Lewis, head of trading and risk at financial betting firm Capital Spreads.

Another difference in style was the absence of sporting metaphors. Mr. King favored references to cricket and soccer to explain central banking concepts to reporters and the nation at large. That audience is less familiar with ice hockey, Mr. Carney’s favored sport.

But Mr. Carney also displayed some of his predecessor’s legendary acerbity. One reporter was swiftly reminded of the difference between the consumer price index and the retail price index when he asked a question. Mr. Carney offered to read another journalist a section of the BOE’s quarterly inflation report that he had presumably overlooked.

Economists broadly welcomed the introduction of forward guidance by the BOE, a strategy already adopted in differing forms by the U.S. Federal Reserve and the European Central Bank. The Confederation of British Industry, an employers’ group, added the certainty that rates should stay low as long as unemployment remains high should give British business and consumer confidence “a shot in the arm.”

Yet some analysts said Mr. Carney’s message could have been clearer, as the guidance was tied to too many variables.

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